1. Field of the Invention
This invention relates to a versatile unit employing single wall magnetic domains and more particularly to an arrangement of such domains to form a selectably programmable arithmetic and logic unit capable of performing a plurality of functions.
2. Description of Prior Art
The controlled movement of single wall domains, or bubbles, in a slice of magnetic material in response to a reorienting magnetic field is disclosed by A. H. Bobeck in U.S. Pat. No. 3,460,116 issued Aug. 5, 1969. Typically, the movement of the domains is controlled by the juxtaposition of a magnetically soft overlay with a surface of the material in which the domains are propagated. The overlay elements are constructed in such a manner that different points become magnetically attractive at different magnetic field orientations, thereby defining a path or channel that is followed by a domain. One such overlay, commonly referred to as a T and Bar overlay, is detailed in the above-mentioned Bobeck patent and is arranged to control the movement of magnetic domains in response to a reorienting magnetic field, illustratively having four quadrants or reorientations, per cycle of rotation. Other Permalloy overlay configurations, such as Chevron patterns may also be employed. In addition, ionimplanted garnet circuits following the organization of the Permalloy circuits have also been developed.
The usefulness of any such device depends upon the geometry of the respective elements with respect to each other. Thus the elements are advantageously arranged to take advantage of the fact that all domains in a slice of magnetic material under the influence of the same rotating field will propagate in that material in synchronous relationship with each other. Accordingly, domains which are propagated along different paths will arrive at certain points of the overlay in a predetermined coordinated relationship. This physical control of magnetic domains in spatial coordination coupled with the interaction forces between domains in close relationship with each other permits consecutive logic operations to be performed between corresponding representations of different sets of information representations solely within magnetic domain technology provided the representations are organized in a form to capitalize on those properties.
It is possible to take advantage of the fact that the physical location of any magnetic domain in such a device is definable in terms of discrete preset element patterns. Hence, it is possible to organize the device or unit to attain various arithmetic and logic or system functions. U.S. Pat. Nos. 3,750,106 and 3,753,253 relate to functional magnetic domain arrangements capable of performing some logic operations. The operation of binary addition, which is very important in computer architecture, is not shown or suggested by these patents. Primarily, this is because of the lack of ability to process "carry" information inherent in adding two serial binary-coded data streams. Neither is the separation of programming signals from data signals, the arrangements disclosed therein including common input channels for both, their differentiation being coded in the data application. This is particularly disadvantageous for a unit capable of performing arithmetic operations, where the serial handling of the data might interfere with programming instruction coding. Further, there is no provision for handling data streams wherein not every bubble is related to a common word.
Accordingly, it is a feature of the present invention to provide an improved magnetic domain logic unit also capable of performing the arithmetic operation of addition.
It is another feature of the present invention to provide an improved magnetic domain arithmetic and logic unit for handling serial data so that the data streams and the control signals are separately applied.
It is still another feature of the present invention to provide an improved magnetic domain arithmetic and logic unit for handling streams of data wherein there are a plurality of data words interleaved therein.